44 British Uredinee and Ustilaginee. 
to be visible; this is probably due to the elasticity of the 
epidermal cell-wall. The germ-tube itself continues its 
onward growth; soon branching, it insinuates itself between 
the cells of the host, where it gives rise to a mycelial 
development, similar to that which arises from the zcidio- 
spore or uredospore germ-tubes. 
With the Leptopuccinia and Lepturomyces, the germ- 
tube of the promycelial spore does not bore its way through 
the epidermal cells, but enters, as De Bary* first showed 
with P. dzanthi, through the stomata, or, as Rathay f points 
out with P. malvacearum, it enters, like the germ-tube of 
Tubercinia trientalis, between the epidermal cells, and then 
pierces laterally into the side of the adjacent cell. 
If the germination of the promycelial spores takes place 
in water, and not upon their proper host-plant, the germ- 
tubes sometimes become swollen at their extremities, so 
as to form reserve spores in the same manner as has been 
previously described with the uredospores (Plate III. 
Fig. 24). 
The mycelium produced from a promycelial spore in 
the tissues of its proper host-plant in due time gives rise 
to a fresh spore-development. This spore-development, 
however, varies in different cases. 
1. In certain species the mycelium produces spores. 
which are exact counterparts of the original teleutospores 
(Micropuccinia). 
2. It may give rise to teleutospores similar in general 
appearance as to its progenitors, but endowed with the 
faculty of immediate germination (Leptopuccinia, etc.). 
3. It may give rise to a crop of uredospores, which may 
* De Bary, “Champ. paras.,” Ann. Se, Nat., 4° sér. tome xx, p. 84 
(reprint). 
+ Rathay, “‘ Ueber d. Eindringen. Puccinia Malvacearum,” Verhandi. d. 
Kk, Zool, bot, Ges., band xxxi. (1881), t. 1. 
